Typical drainage systems collect surface water within underground drainage systems to prevent flooding. In a typical drainage system a number of inlets are connected to an underground storm sewer system. An inlet typically includes a removable cast iron grate that inhibits the flow of some large debris into the inlet. The grate may include openings of up to four inches or longer and allows the flow of debris into the drainage system. The debris builds up within the drainage system and will block the flow of water through the system and may cause localized flooding. In order to maintain the flow of water it is necessary to clean the drainage system. This cleaning is typically performed with a great deal of physical effort and a truck equipped with a vacuum hose to remove the debris from the system.
It is known to place a filtering screen above or below the storm drain grate to collect smaller items of debris that may pass through the grate. These prior art filters are easily blocked by a buildup of debris or soil on the filter. Complicated structures have been developed to allow an increased sump area for collection of debris within the catch basin. These structures require rings or hooks that penetrate and weaken the filter media. Another prior art device, as shown in U.S. Pat. No. 6,294,095, includes a frame that is inserted into the drainage system and a number of rods that are fitted to and retained by the frame to retain the filter media.